1. Field of the Invention
This invention is in the field of gas separators which utilize a surface force material across which a mixed gas flows in order to be separated into two or more differing product gases. Also, this invention is among those gas separators of this type which utilize cyclic flow of gases during the separation process.
2. Description of the Prior Art
It has long been known that a mixed gas can be at least partially separated by causing the mixed gas to flow across the surface of a material which exerts an attractive force upon the molecules of the mixed gas provided the force differs among at least some of the differing molecules of the mixed gas. The surface force material which exerts the force of attraction upon the gas molecules can be a solid or a liquid or mixtures thereof. The separating action appears to result from the fact that those molecules more strongly attracted to the surface are captured thereon for a time of delay and hence are left behind by the onward flow of those molecules not strongly attracted to the surface. As gas flow continues the surface approaches an equilibrium amount of molecules captured on the surface after which the separating action ceases. For this reason, prior art gas separators of this type have used intermittent flow or cyclic flow of the mixed gas across the surface in order to achieve useful separations. The surface is then at least partially purged of captured molecules between flow periods in order to restore the separating ability. The term chromatographic separator is sometimes applied to cyclic gas separators of this type due to their widespread use in gas chemical analysis.
Some examples of prior art cyclic gas separators using surface force materials and cross flow for separation are as follows:
The basic principles, suitable materials, and operating methods of prior art cyclic gas separators are described in several prior art references of which reference A is an example.
These prior art cyclic gas separators necessarily use a purge gas and a purge cycle to remove the molecules held by the surface force material in order to restore the separating capacity of the surface force material. Hence, these surface held molecules are only recovered intermittently and diluted into the purge gas. It would be advantageous to have available a cyclic gas separator which delivered the separated gas products continuously and in an undiluted form more suitable for subsequent use. Additionally, it would be advantageous to have available a cyclic gas separator which did not require a supply of purge gas for its operation. These prior art cyclic gas separators also deliver those molecules captured by the surface force material as a single and diluted gas product which is not separated further into additional differing gas products. Thus, it would be further advantageous to have available a cyclic gas separator capable of separating a mixed gas into two or three or more differing and undiluted gas products.
References:
A. "Gas Chromatography," H. Purnell, John Wiley, New York, 1962.